Muscle tissue is the most abundant tissue in mammals, and is mainly responsible for generating force to cause movement of various parts of the body. Muscle can be divided into three groups: skeletal muscle, cardiac muscle and smooth muscle. Based on the metabolic types and characteristics, skeletal muscle can be divided into slow twitch muscle and fast twitch muscle, wherein the former consists of slow-twitch fiber proteins that can twitch for a longer period, but the generated force is weaker; the latter consists of fast-twitch fiber proteins that can twitch faster and stronger than the former, but fatigues more easily.
Under normal physiological conditions, there is a dynamic balance between the synthesis and degradation of muscle proteins. However, when an imbalance of muscle protein metabolism occurs (namely, the degradation rate of muscle proteins become greater than the synthesis rate), it causes loss of muscle. Severe muscle loss leads to muscle atrophy and characteristic changes, such as a decrease in muscle mass, a reduction of muscle fiber cross-sectional area, and a selective reduction of muscle fiber type-related proteins (i.e., slow-twitch fiber proteins and fast-twitch fiber proteins), which can result in symptoms that seriously affect daily work and vital function, including a reduction in muscle strength, movement disorders, fatigue, metabolic disturbances, etc.
It is known that muscle cell injury can be caused by various physiology conditions or specific diseases that lead to muscle cell metabolic disturbance or apoptosis of muscle cells, causing muscle loss. Factors leading to muscle loss include, for example, neurodegeneration, long-term bed rest, aging, diseases, cachexia (e.g., cancer cachexia), etc., wherein the diseases include sepsis, acquired immune deficiency syndrome (AIDS), renal failure, Cushing syndrome (CS), sarcopenia, cancer, chronic obstructive pulmonary disease (COPD), congestive heart failure (CHF), trauma, etc.
Aging is the major factor causing sarcopenia. Statistical data indicate that the incidence rate of sarcopenia among those aged 60˜70 is 13 to 24%, while the incidence rate of sarcopenia among people older than 80 years of age is about 50%. Besides, in America, the medical costs caused by sarcopenia per year is about 11.8 to 26.2 billion USD. While cachexia relates to other diseases having high incidence rates, for example, about 50% of patients with cancer, 20 to 40% of patients with COPD, and 50 to 70% of patients with CHF will exhibit the symptoms of cachexia (e.g., dystrophy).
Herba Cistanches was firstly recorded and rated as a top-grade herbal remedy in “Shennong Bencaojing” (The Classic of Herbal Medicine). Herba Cistanches is effective in nourishing the kidneys and invigorating yang, boosting essence and blood, lubricating the bowels to relieve constipation, making it the Chinese medicine prescribed most frequently by physicians for kidney nourishment and yang invigoration. Cistanche tubulosa is a kind of perennial parasitic herb belonging to the family of Orobanchaceae and the genus of Cistanche, which is found in the desert and other dry areas and subsists on absorbing nutrients from its host plant, Red willow. That is, Cistanche tubulosa is a precious and rare medicinal material. Cistanche tubulosa association with, for example, renal function improvement, memory enhancement, immune function regulation, anti-dementia disease, anti-aging, and anti-fatigue were published in “Pharmacopoeia of the People's Republic of China” in 2005.
In the clinical practice, there is still a lack of an effective method for treating or delaying muscle loss, and the effects of Cistanche tubulosa on protecting muscle against atrophy have not been presented on any documents so far. Therefore, to develop a more effective method for treating or delaying muscle loss, the inventors of the present invention selected Cistanche tubulosa from the traditional herba, and then investigated the feasibility of using Cistanche tubulosa in protecting muscle (namely, protecting muscle cells against injury and preventing muscle loss). The inventors of the present invention found that the Cistanche tubulosa extract and isoaceteoside contained therein are effective in protecting muscle cells against injury. Therefore, the Cistanche tubulosa extract and isoaceteoside can be used for regulating, treating and/or delaying muscle loss, especially for regulating, treating and/or delaying muscle loss caused by aging, disease and/or cachexia, and thus can be used for providing a pharmaceutical composition, a medicament or a food product that can protect muscles.